Field of the Invention
The presently disclosed subject matter relates to an inkjet recording device and a maintenance method thereof. Specifically, the presently disclosed subject matter relates to an inkjet recording device in which a liquid-repellent film is formed on a nozzle surface of an inkjet head and a maintenance method thereof.
Description of the Related Art
When dirt such as ink and paper powder adheres near a nozzle opening in a nozzle surface of an inkjet head, it becomes likely to cause defective ejection such as bending of the ejection direction of an ink drop from the nozzle opening. Therefore, the nozzle surface of the inkjet head is subjected to liquid-repellent treatment so as to prevent dirt from adhering near the nozzle opening.
However, even in a case where the nozzle surface is subjected to the liquid-repellent treatment, it is not possible to completely prevent dirt from adhering to the nozzle surface. Therefore, a cleaning of the nozzle surface is periodically performed.
The cleaning of the nozzle surface is generally performed by wiping off the nozzle surface by a blade (wiper) or a wiping cloth. However, when the cleaning is repeatedly performed, there is a problem that the liquid-repellent film formed on the nozzle surface gradually comes off and the liquid-repellent performance degrades. As an example, in an inkjet head in the related art, a contact angle of ink with respect to a nozzle surface is measured after the cleaning of the nozzle surface is performed 1000 times, and the measured contact angle decreases by about 20% as compared with a contact angle of ink with respect to the nozzle surface before the cleaning. In a case where the contact angle of ink with respect to the nozzle surface decreases by 20%, it is difficult to hold meniscus of ink in the nozzle. There occur problems that the ejection direction of an ink drop from a nozzle opening bends or ejection is completely impossible, and so on.
To solve the above-mentioned problems, Japanese Patent Application Laid-Open No. 08-187876 and Japanese Patent Application Laid-Open No. 08-281962 suggest a technique of applying a liquid-repellent agent to a nozzle surface to and recoat the nozzle surface every time the nozzle surface is wiped off and cleaned.
Japanese Patent Application Laid-Open No. 2008-183853 suggests a technique of reducing a pressing pressure of a wiper member with respect to a nozzle surface and preventing a liquid-repellent film on the nozzle surface from being worn out by forming the wiper member that wipes off the nozzle surface with a plurality of wiper parts.